DE 199 44 620, which was published afterwards, discloses an aircraft passenger seat having individual seat components including a leg rest and a backrest. These seat components can be moved by actuation means in the form of servo-drives or actuators triggered by a hand-operated actuating means for adjusting the seat to the requirements of the seat occupant. For the seat parts, hand levers are modeled to the contours of these seat parts as an element of the actuating means, and are combined with an operating part for adjusting the aircraft passenger seat for adjustment for the respective seat component. To prevent the seat occupant from striking fixed barriers when adjusting the seat components to his requirements, for example, against the rear area of the backrest of a seat following ahead in the lengthwise direction of the seat, the servo-drives have stops against which the respective seat components extend. The pertinent respective stop barrier cannot be passed, even as the pertinent control button continues to be actuated. Another possibility is to turn off the drive by cam-operated limit switches. The pertinent limiting barriers are not always approached without jerking in the known seat designs. This jerking can adversely affect sitting comfort. The respective seat component is also protected by stops in the maximum deflection positions. In case of a crash, this arrangement can lead to the seat frame structure, including the stationary legs, collapsing and accordingly adversely affects the safety of known seat designs.
DE-A-40 03 776 discloses a vehicle seat, especially a motor vehicle seat, with a cushioned support of the seat part adjustable by an adjustment device relative to the freely-swivelling backrest At least in one position of the cushion support above its lowermost position, the cushion support of the seat part is movable back into the initial position by the adjustment device before or at the beginning of freely swivelling the backrest out of its initial position forward and/or at least in the area of its back end section down and after or during swivelling back the backrest into its initial position. Although the known adjustment device can also be used for adjusting the height or tilt of the cushioned support of the seat part, the adjustment possibilities for the individual seat parts are reduced even if in one advantageous configuration of the known design the rocker of the adjustment device is coupled to an adjustment element of variable length which can be, for example, a motor-driven threaded spindle or a working cylinder.
U.S. Pat. No. 2,784,764 discloses a generic seat with two pairs of stationary legs which engage the seat part with a swivelling capacity, and engage the floor mounting device for the seat. Between the stationary legs, an actuator in the form of a roll spindle device extends. One actuator end in the area of the front seat edge points opposite the floor structure. The other actuator end in the area of the rear set edge points in the direction of the seat frame structure. The one free end of the actuator is movably coupled to a control part. The control part is connected to a U-shaped seat rail having a link guide for a rod-like stiffening part. The stiffening part extends transversely to the lengthwise direction of the actuating means in the initial state, and consequently in the raised position of the seat part, extends between the rear stationary legs and the indicated lengthwise link guide. Although the known design is made very stiff, and consequently must be adapted to safety requirements which are higher in a crash. With the known design, it is only possible to adjust the seat part in an incline which has been permanently assigned once to different seat heights, and in this way, to match the requirements of the seat occupant.